ALBERT

Notes: Abstract. The efficient management of clay soils depends on the rapid disposal of water following rainfall. Winter storm outfall hydrographs of under drained catchments ranging in size from 0.44 ha to 7.2 km2 are given, illustrating the drainage response of a Windsor Series soil. The response time of different sized catchments is discussed in relation to potential flood hazard arising from drainage improvements of agricultural land. Comparison is made with other soils to reveal broadly similar patterns of drainflow, with peak flow occurring typically between 1 and 4 hours after the mid-point of a storm. Despite large fluxes of water through the soil profile, the water content of the soil within the catchment of an individual tile lateral is shown to vary only by small amounts both during and after a single rainstorm and over a drainage season.

Notes: Abstract. The salt regimes in soil under grazed and ungrazed natural grassland were compared on a Natraquoll in the Flooding Pampa of Argentina. The salt concentration in the topsoil of the grazed land increased sharply and episodically after flooding, whereas in the ungrazed land it did not.When the area was flooded groundwater rose and increased the salt content of the deep horizons. Thereafter the topsoil became salinized during drought when the atmospheric water demand was large. The evaporation from the soil surface in the grazed area was faster than in the enclosed field, being probably the cause of the accumulation of salts in the topsoil.

Notes: Abstract. Nitrate losses from a small catchment of mixed land use in south Devon, England, are described. The temporal pattern of leaching is dominated by major losses through the winter months when both streamflow and nitrate concentration are large. Storm runoff is generated mainly by subsurface stormflow, and nitrate losses are particularly important at such times. The spatial pattern of nitrate loss from the catchment is controlled both by land use and by topography.

Notes: Abstract. Nitrate concentrations measured in an ephemeral stream draining a 170 ha clay catchment in eastern England, with about 23% arable land, were greater than 11.3 mg N 1–1 on the resumption of flow each autumn but then declined. There was also a spring peak in two years out of seven, 1978–1984, which depend on the length of time soils was at field capacity in the preceding winter. Mean annual load measured in rain was 19 kg N ha-1 and loss of nitrate in the stream 34 kg N ha-1. A catchment nitrogen balance suggested that inputs, which averaged 130 kg N ha yr-1, were generally more than outputs, average 108 kg N ha yr-1', but gaseous losses were not taken into account.

Notes: Abstract. Soils derived from basalt bordering the northern Jordan Valley have developed under semi-arid to humid Mediterranean conditions and belong to two major soil orders: Vertisols in the drier south and Alfisols (Brown and Red Mediterranean soils) in the more humid north. Major limitations on land use of the vertisols are low hydraulic conductivity, slow infiltration and strong susceptibility to erosion by water. Crops growing on basalt-derived soil also suffer from phosphorus deficiency, though the soils contain much inorganic phosphorus. The natural vegetation is mainly herbaceous and grows well even under intensive and continuous grazing. The land is best used for pasture wherever limitations restrict other uses.

Notes: Abstract. The analysis of some experimental field results is used to illustrate the problem of measuring and evaluating compaction treatment effects below wheel ruts of different depths. A solution to the problem is described which traces vertical soil movement to allow comparisons between treatments to be made using soil elements which derive from the same depth in the undisturbed profile, irrespective of their depths in the compacted profile.A soil compaction model, which predicts the changes in dry bulk density resulting from the passage of wheels, is briefly described. Examples are given of its use in comparing the compaction caused by various types and arrangements of wheels and in assessing the contribution made by a particular input variable.

Notes: Abstract. The paper presents the experimentally derived state boundary surfaces of critical state theory for a sand, a loam and a clay soil. Orderly changes to these surfaces with moisture content and two soil micro-structural states have been identified. These findings are used as the basis for the formulation of a fairly simple universal model of the geometry of critical state space for unsaturated soils. Examples are given of how this model can be used to explain known soil behaviour in many practical situations. The indications are that this model can provide the theoretical framework for a fundamental comprehension of the many complex processes involved in soil loosening and compaction. There is, as yet, no simple experimental technique for measuring the critical state boundaries of field soils and this is a major impedement to the development of the model as a practical soil management tool.

Notes: Abstract. The soil forces acting upon agricultural discs arise from both a passive reaction on the concave face and scrubbing reaction on the convex face. The magnitude of these reactions is a function of both the disc geometry, primarily the radius of the sphere from which the disc is formed, and the angle of the disc to the direction of travel. These forces can be predicted within acceptable limits using soil mechanics theories based upon Mohr-Coulomb properties. From both the theoretical and practical results optimum disc setting can be selected to give low specific resistance values. The prediction model has been successfully used with stress analysis techniques to design new disc geometries and, with the advent of improved materials, to select appropriate disc thicknesses.

Notes: Abstract. Between 1978 and 1985 16 experiments tested crop response to subsoil loosening by either the Wye Double Digger or a winged subsoiler. Additionally, response to incorporation of 350 kg ha of P2O5and K2O into the subsoil was tested. Soil types were mainly well-drained light-and medium-textured soils in arable rotations. Subsoil loosening increased the yield of spring-sown crops on sandy soils in years of moderate to severe drought. Response was associated with deeper rooting and improved water extraction from the subsoil. No yield increases were recorded with autumn-sown crops which were largely grown on the medium and heavy textured soils. There was a trend towards yield reductions on deep silty soils in wetter years. At one site only did the response to phosphorus and potassium fertilizer incorporated into the subsoil exceed that of fertilizer applied to the topsoil.

Notes: Abstract. In a series of experiments on 16 sites both a power-driven rotary-tine Wye Double Digger and a rigid tine winged subsoiler produced significant subsoil loosening and fissuring. The Double Digger consistently produced the greatest clod breakdown together with the least soil bulk densities and cone penetration resistances. Management strategies after loosening had an important influence on the longevity of the loosening effect. The rate of recompaction was least with controlled traffic and bed systems and increased with random traffic and with the growing of root crops. No significant differences in crop response were monitored between the two loosening treatments, yield response depending largely on the extent of moisture stress experienced by the crop. Loosening on silty soils reduced yields in wet seasons and this was associated with soil structural instability. Visual soil profile examination is necessary to support bulk density and cone penetration resistance measurements when assessing soil compaction.

Notes: Abstract. Dryland regions are found in both tropical and middle latitudes. In the former, rainfall occurs mainly as a result of convection giving greater spatial variation than in the latter, where much rainfall is associated with frontal systems. The year-to-year variation in rainfall regimes is illustrated with examples from dryland regions in Kenya, Botswana and Syria. The importance of the fact that most rain occurs on few rain days is discussed. Although forecasting of rainfall is not possible, crop management can be improved by taking into account the current state of the rainy season. The need for an effective description of the rainfall regime is emphasized.

Notes: Abstract. This paper summarizes the essential features of the Mediterranean climate and its associated soils and farming systems. Rain falls mainly during the winter so that crops must usually rely on stored soil moisture when they are growing most rapidly. Water use efficiency of dry matter production can be increased in three ways but chiefly by decreasing evaporation from the soil surface. Soil and crop management techniques used to increase water use efficiency are reviewed.

Notes: Abstract. Meteosat is a geostationary satellite which observes the earth from the same point every half hour and views many of the drylands of Africa. Its data can be processed to provide information on the state of the surface of the earth, and its moisture condition in particular, by evaluating the thermal inertia from observations of the diurnal temperature cycle of the surface. This method is limited by the simple radiometry and low spatial resolution of Meteosat. The surface temperature amplitude cannot be known to better than 2°C, and the heat flow into the ground to 20%. As a result the actual values of thermal inertia can be known only to this accuracy.Interpretation of thermal inertia is ambiguous, and alternative interpretations of any given value are discussed, showing little information on conditions more than 10 cm below the surface, and limited discrimination over soil moisture contents even in the topmost layer. Despite these difficulties, thermal inertia values could be calculated routinely. This could give information on the detailed distribution of rain from convective storms for agricultural monitoring and for large-scale meteorological models.

Notes: Abstract. Spring wheats are sown in autumn and mature under conditions of spring water deficits in Western Australia. While grain yields are very small (averaging 1.05t ha-1), water-use efficiencies (WUE) of crops grown with good management compare favourably with the rest of Australia at 10 kg grain ha-1 mm-1. Major water loss, calculated at an average 40% of growing-season rainfall, occurs through evaporation from the soil surface, and in some years significant losses also occur through deep drainage on sandy soils. Evaporation losses can be reduced by stubble retention and adding gypsum to improve filtration on structurally unstable, fine-textured soils. More general increases in crop water use occur through all agronomic factors which result in rapid and uniform plant cover as early as possible after break of season. This includes adequate fertilization, weed control and narrow row-width. Wheat crops sown after pasture and grain legumes consistently outyield all-cereal rotations.

Notes: Abstract. This paper draws on the results of a five-year project on the agronomy, crop physiology and soil physics of the cropping of sorghum and subsidiary crops at several sites in Botswana. The low and erratic yields usually obtained stem largely from the low and erratic rainfall, the harsh physical properties of the soils and the unfavourable interactions between these factors. Deep ploughing is essential to allow root penetration and water retrieval from depth in soils of high bulk density; sorghum plant densities must be kept moderately low, at the price of increased surface evaporation, to ensure that plants are big enough to optimize harvest index; and intercropping with cowpeas should be avoided, since it decreases sorghum yield stability with little appreciable compensation. One essential for a more stable, higher-yielding cropping system is the year-round management of the soil as a water storage medium. This will require the alternation of short periods of bare fallow with a sequence of crops with short and long growth cycles.

Notes: Abstract. Tillage practices for water conservation in the Pacific Northwest, USA, wheat region emphasize the infiltration and retention of winter rain and snow and suppression of evaporation and transpiration by weeds. The wheat-fallow system dominates in the semi-arid areas and winter wheat-spring crop rotations are most common in the sub-humid areas. The main features of water conservation during the fallow season include chisel ploughing in the autumn to reduce winter runoff, and spring and summer tillage to kill weeds, minimize evaporation, and conserve seed-zone water. Water in the seed zone is conserved by establishing a soil mulch having properties that thermally insulate the seed zone while at the same time restricting upward liquid and water vapour flow. Water conservation in the more humid zones involves chisel ploughing in autumn, uphill ploughing, and stubble retention to reduce winter runoff. New practices include minimum tillage and no-till planting methods which maintain surface residues. However, heavy equipment associated with current trends in no-till is causing soil compaction which may decrease infiltration rates. Methods under experimentation to improve infiltration with conservation tillage systems include slot mulching, paraplowing, and the use of basin pitters.

Notes: Abstract. Hard-setting soils are widespread in dry regions. Their properties are described and a physical explanation for hard-setting behaviour is given. The limitations on soil management and physical fertility caused by hard-setting depend on timing of rainfall or irrigation with respect to cultivations and crop development, and much research is needed to quantify reductions in crop yield imposed by these limitations.

Notes: Abstract. The paper presents an introduction to automated methods of classification and assignment, with particular reference to their use in the analysis of soil data. Material covered includes: types of variable describing a soil sample; measures of dissimilarity; clustering criteria and algorithms; representation of data as points in a low-dimensional space; assessment of classifications; incorporation into a classification of spatial relationships between soil samples; assignment of objects to the population with maximum posterior probability; assignment procedures for data described by variables of mixed type; kernel density estimation; assignment to spatially-located populations.

Notes: Abstract. Geostatistics is principally the application of regionalized variable theory. The methods it embodies are applicable throughout the earth sciences for investigating the spatial variation of, and for estimating continuous random variables. The semi-variogram is the central tool of geostatistics. It can quantify the scale and intensity of spatial variation and it provides the essential spatial information for local estimation by kriging and for optimizing sample intensity. It can also be used in an exploratory manner to try to discover underlying causes of the variation. Geostatistical methods have been widely applied in the mining industry and there are many examples of their application in soil science. Their use is illustrated by a case study of soil spatial variation in the Wyre Forest of England.

Notes: Abstract. Rural planning studies require knowledge about the attributes and spatial distributions of the natural resources of areas to be developed. When these data are available only in the form of paper maps simple technology limits the planner in the number of questions that can be answered quickly and effectively. Geographical information systems now enable mapped data to be stored and linked to other relevant spatial information so that many kinds of questions about the natural resources can be answered, and various scenarios can be compared before they are carried out. The methods used for data analysis in geographical information systems are explained briefly and are illustrated by using an example of locating a simple earth dam in a small catchment in Kisii District, Kenya. Although these new tools are often technically excellent, the results they give can be no better than the quality of the data and the models used for analysis allow. There is still much work to he done on the propagation of errors in geographical analysis, whether done with the aid of the computer or not.

Notes: Abstract. Computer-compatible proformas have been designed to incorporate soil descriptions into automated soil information systems. This paper presents two systems designed to replace proformas by enabling the direct entry of soil descriptions into computers. One, CASTS (Computer Aided Soil Thin Section description), is in essence a computerized glossary of the terms used to describe soil thin sections. The terms are organized into menus that are presented to the user in a fixed, logical sequence. The system runs on an Apple microcomputer or VAX minicomputer. The other, SPR (Soil Profile Recorder), is for use in the field on the Husky Hunter lap computer. The program enables descriptions from soil auger-borings to be recorded, and has facilities to manipulate entries and transmit them to a central information system. These computer systems are compared with the proformas, and recommendations are made for incorporating improvements in future versions.

Notes: Abstract. An automated system for the chemical analysis of large numbers of soil samples from a national survey has been developed. Computers are used for the quality control and the management of the resulting data. The software for this includes checks for possible errors thereby minimizing them. Human intervention is necessary only to correct them. Additionally, the data are analysed statistically and the geographical distribution automatically displayed in map form. Much of the software runs interactively, enabling rapid reporting of results and mapping of specific areas cheaply and swiftly with little effort from the operator.

Notes: Abstract. A computer simulation model is described which estimates the amounts of nitrogen in the soil and winter wheat crop in spring at the time when farmers require fertilizer advice. The model has been validated against five years of experimental data on several different soil types in the east of England. Various practical applications of the model are described.

Notes: The effects of grassland invertebrates on organic matter decomposition, soil fertility and plant growth are reviewed. Their role as primary decomposers is limited because of relatively low rates of metabolic and enzymatic activity compared with microorganisms. However, they greatly facilitate decomposition by fragmenting and incorporating litter into the soil and by stimulating microbial activity. Earthworms are the main litter consumers in productive temperate grasslands and termites in the tropics, while the activities of dung beetles, dipterous larvae and earthworms are essential for efficient dung decomposition. Earthworms and microbial-feeding invertebrates facilitate mineralization and release into the soil solution of plant nutrients. Earthworms have a major influence on soil structure through burrowing, soil ingestion and mixing and they significantly increase plant growth.Herbivorous invertebrates at non-outbreak densities normally consume less than 10% of net primary production in grassland, but consumption bears little relationship to overall effects on productivity. These depend on factors such as the nature of the damage caused and regrowth potential, tolerance for damage and effects on animal production at the time of attack. Sap feeding insects may cause wilting and reduced growth and selective feeding on preferred species can alter botanical composition, while aphid-transmitted virus disease can depress yield. On the positive side, low levels of herbivory can stimulate growth, weed feeding insects may limit the distribution of pasture weeds, while the role of flower-visiting insects can be important in the pollination of legume seed crops. Pest management approaches incorporating biological control, alteration of botanical composition, adjustment of stocking densities and accurately timed insecticidal applications offer prospects for the control of recurring pests such as grass grub and porina in New Zealand.

Notes: Leatherjacket populations were sampled from 20 sites in Northern Ireland by collecting 10 cm diameter soil cores and wet sieving. The sample variances were linearly related to the sample means. Up to a mean of 1.14 leatherjackets per core, populations could be described by the Poisson distribution. Negative binomial distributions could also be fitted to data where the sample variance was greater than the sample mean. A strong curvilinear relationship was found between the sample mean and the proportion of cores containing leatherjackets. The raw data were used to generate a series of equations which in turn gave rise to a function linking frequency, sample mean and sample size.The implications of these results are discussed in relation to population estimation and advice to farmers.

Notes: The effects of three defoliation treatments upon the performance of eight white clover varieties when grown with S23 perennial ryegrass were investigated. These treatments included a cutting only regime as used in National List trials and rotational and continuous sheep grazing.There were significant (P〈0·001) differences between treatments, and the ranking of clover varieties also differed between the three treatments. The significance of this finding is discussed in relation to the evaluation of breeding material and varieties prior to recommendation to farmers.Clover yields were less under grazing than cutting. This was due mainly to the selective grazing and removal of stolon material which occurred in the former treatments. Differences in the grass/clover balance resulting from the three treatments are discussed in relation to the degree of protection afforded to the clover stolons by the grass component.

Notes: The results are reported of a 2-year plot experiment investigating the potential of lucerne as a silage crop in a comparatively high-rainfall area (annual average of about 900 mm). The performance of the lucerne on the remainder of the field in which the plot experiment was located is also discussed. With below-average rainfall in the sowing year a good establishment was obtained and a single cut to a stubble height of 75 mm in August gave a dry matter yield of 3 t ha-1. In the first harvest year, summer rainfall was again below average and a total dry matter yield of 13·8 t ha-1 resulted from three cuts to 75 mm above ground level. However, the total yield was reduced to 10·11 ha-1 in the second year when the rainfall was considerably above average. Attempts to increase the feeding value of the lucerne herbage by increasing cutting frequency and by increasing cutting height showed little effect over the standard system of three cuts to a stubble height of 75 mm. The effects of applying potassium fertilizer at rates supplying 100,200 or 300 kg K ha-1 either as a single spring dressing or in equally divided dressings were not significant in either of the two years

Notes: The productivity of a mixed sward, comprising perennial ryegrass cvs Barlano and Bastion and white clover cvs Donna and Aran, was measured under sixteen fertilizer N treatments. These involved 0.25, 50 and 75 kg N ha-1 in spring only, in autumn only and in all combinations of spring N and autumn N. A simulated grazing regime of six cuts annually at 3- to 6-week intervals was imposed.Increasing rates of total N application increased total herbage DM regardless of application pattern. Yield response was greater with N applied in the spring, and total herbage DM was higher with high spring N-low autumn N than the reverse. Mean yield responses at the first harvest to 25, 50 and 75 kg ha-1 N in spring were 13.6, 10.8 and 11.6 kg DM per kg N. Corresponding responses at the final harvest to N rates in the autumn were 7.2, 5.8 and 6.8 kg DM per kg N. Responses were similar at these times for treatments receiving combined spring and autumn N.Over all treatments, mean annual production of total herbage was between 7.08 t ha-1 DM with no N and 8.19 t ha-1 with 75 kg ha-1 N in both spring and autumn. Owing to drought, mean production in year 2 fell by 32% compared with year 1.White clover production fell progressively with increasing N application. Treatments with spring-applied N gave the most marked decrease. White clover was more markedly depressed than the associated grass by the drought in the second year. The mean reductions in white clover content were 0.17, 0.07 and 0.12 percentage units per kg applied N for spring N, autumn N and combinations. Autumn N use depressed white clover less than spring N but the yield response of grass was less.It is concluded that any applied N adversely affects white clover performance to some degree. Where management factors are unfavourable to white clover even strategic N use may not be wise. Instead, it is suggested that a ‘dual-sward’ approach be adopted in practice, namely, grass/white clover swards with no N. and complementary grass swards receiving optimum applied N to give better production at times when grass/white clover swards are relatively less productive.

Notes: The main factors affecting the abundance and composition of the invertebrate fauna in grassland are reviewed. Old grasslands with species-rich swards and complex structure support an abundant and diverse fauna compared with uniform leys with few species. Seasonal and successional changes in the sward are accompanied by equally marked changes in the invertebrate community. Climate and weather have a major influence, but their effects may be modified locally by the availability of shelter. Soil physical and chemical characteristics influence the soil fauna directly and the above ground fauna indirectly through the vegetation. Food quality as determined by physical and chemical plant characteristics strongly influences invertebrate growth, reproduction and mortality. The main biotic factors affecting abundance are natural enemies and disease; these, in combination with weather and food quality, are often the main agents in determining population density in natural communities.Management practices such as grazing, cutting, fertilizer application, burning, soil water control and pesticide use profoundly influence the sward and induce correspondingly great changes in the invertebrate community.

Notes: Four varieties of white clover (small-leaved cv. Aberystwyth S184. medium-leaved cv. Grasslands Huia and large-leaved cvs Linda and Olwen) were sown at 3 kg ha-1 together with 10 kg ha-1 perennial ryegrass cv. Talbot. Herbage productivity was measured for three harvest years, 1979-81, over four annual rates of fertilizer N (0,120,240 and 360 kg ha-1) and two closeness of cutting treatments (80 and 40 mm from ground level). A simulated grazing regime of six cuts per year at 3- to 6-week intervals was used.Production of total herbage DM was increased by increasing N rate; mean annual DM production ranged from 783 1 ha-1 with no N to 11701 ha-1 at 360 kg ha-1 N. Mean herbage response to N (kg DM per kg N applied) was 73,90 and 108 for the three successive N increments relative to no N. Mean white clover DM production was reduced from 4 14t ha-1 with no N to 051 t ha-1 at 360 kg ha-1 N.The large-leaved clover varieties were more productive than the small- or medium-leaved varieties at all N rates. Close cutting increased total herbage and white clover by a mean annual 16% and 31%. respectively. White clover varieties did not interact with either N rate or closeness of cutting.It is concluded that repetitive N application over the growing season is incompatible with white clover persistence and production, even with large-leaved clover varieties or with close cutting, two factors which improved clover performance in the experimental swards.

Notes: Swards of perennial ryegrass/white clover were cut to 3 cm in March and allowed to regrow for approximately thirteen weeks. Half the swards received nitrogenous fertilizer at the time of cutting (+N treatment) while the other half received none (—N treatment).About four weeks after the application of treatments, the number of clover shoots in the — N treatment was significantly higher than that in the +N; at this stage total leaf area index on both treatments was low, but significantly greater in the + N. After 30 days, more light was reaching ground level in the — N treatments, and about 40 days after cutting there was between 17 and 50% more clover in the — N treatment than the +N.It is suggested that the inhibition of stolon branching with a consequent restriction in the rate of increase of clover leaf area is a major factor in the adverse effect of N fertilizer on clover.

Notes: Field experiments in 1981 and 1981 examined assimilate distribution in lodged and non-lodged plots of perennial ryegrass (Lolium perenne), cv. S24, grown for seed. Lodging was prevented either mechanically (1982 only) or chemically, by application of paclobutrazol (PP333) at 2 0 kg a.i. ha-1. For each treatment, main-tiller ears, stems and leaves and subtending vegetative tillers were fed with 14CO2 at 24 and 17 days after anthesis in 1981 and 1982, respectively, and the pattern of 14C-assimilate export from each fed part was determined.Prevention of lodging increased assimilate movement to the ear from the flag leaf, although movement from main-tiller leaves was primarily downwards to vegetative tillers. Assimilate movement to the stem was also increased because the cessation of stem elongation was delayed, especially where lodging was prevented by PP333. Both increases were at the expense of the tillers, although their number was not reduced in non-lodged plots. Possible reasons for these changes in assimilate distribution are discussed.

Notes: The residual standard deviations and distribution of residuals around five models were used to investigate the relationship between recordings from an electronic pasture probe and dry matter harvested from annual pastures (predominantly subterranean clover) at low levels of green feed on offer. Pasture material harvested was that considered to have the greatest influence on the probe i.e., within 5 cm of it.The following conclusions were drawn. When measuring short dense green pastures yielding up to 3000 kg dry matter ha-1 the model best describing the relationship is a split line. Curvilinear models are better than a linear model; however, both single linear and curvilinear models give biased estimates particularly near the middle and at the lower end of the range.The best fitted model is discussed in terms of the structure of the sward and the probe.

Notes: Three change-over experiments were conducted to determine the effect on ad libitum silage intake and milk production in dairy cows of treatment of barley supplements with an acid-formaldehyde reagent designed to reduce the rate of starch and protein digestion in the rumen. In Experiment 1 there were six dietary treatments consisting of silage with supplements of 4·0,6·5 and 9·0 kg d-1 of barley given untreated or treated with formaldehyde reagent (8·1 t-1). In Experiment 2 there were four dietary treatments consisting of silage with supplements of barley (7·0 kg d-1) or barley and fishmeal (6·0 kg d-1 plus 1·0 kg d-1), with the barley untreated or treated with formaldehyde reagent (15·1t-1). In Experiment 3 there were four dietary treatments consisting of silage given alone or with supplements of barley (9·0 kg d-1). Treated barley (15·1 t-1, 9·0 kg d-1) and barley plus sodium bicarbonate (9·0 kg d-1 plus 25·0 g d-1).Treatment of the barley supplement with formaldehyde reagent had no effect on silage intake or milk production in Experiment 1 where the rate of application of the reagent was low and the basal silage-barley diet was limiting in rumendegradable nitrogen. However, in Experiments 2 and 3 treated barley supplements were associated with improvements in silage intake and milk production. As compared with corresponding control diets containing untreated barley, increases in silage intake ranged from 0 to 0·16 of the control value, whilst associated increases in the yields of milk, milk fat, milk protein and lactose were 0·077–0·089, 0·016–0·026, 0·092–0·118 and 0·080–0·092 of the control value. These responses are discussed in relation to the increases in silage intake and milk production observed with fishmeal supplementation of the diet in Experiment 2 and inclusion of sodium bicarbonate in Experiment 3.

Notes: A total of 1713 samples of silage from commercial farm silos were analysed to investigate the effect of dry matter (DM) content and chemical additives on fermentation as measured by ammonia-N concentration and pH, Increasing DM content without additive use had a major beneficial influence upon fermentation. When silage DM contents were greater than 260 g kg-1 83% of silages were well fermented, with average ammonia-N concentrations of 94 g (kg total N)-1 and pH 4.36. With diminishing DM concentration the proportion of well fermented silages declined. In the DM range 220-260 g kg-1 67% of silages were well fermented with ammonia-N concentrations of 125 g (kg total N)-1 and pH 4.30, in the DM range 180-220 g kg-1 48% were well fermented with ammonia-N at 151 g (kg total N)-1 and pH 4.38 and with DM below 180 g kg-1 no silages were well fermented with ammonia-N concentration of 252 g (kg total N)-1 and pH 4.84.The benefit of chemical additives, albeit at poorly defined and often inadequate rates, was small in comparison to that of increased DM concentration. Below DM concentrations of 180 and 220 g kg-1, the only benefit was that formic acid decreased ammonia-N to 151 g (kg total N)-1 and pH to 4.32 compared with 163 g (kg total N)-1 and pH 4.43 for untreated silages. Within the DM range 220-260 g kg-1 formic acid decreased ammonia-N level to 104 g (kg total N)-1 and pH to 4.07, and there was a slight benefit from using sulphuric acid/formalin which decreased ammonia-N to 117 g (kg total N)-1 and pH to 4.23 compared with 125 g (kg total N)-1 and pH 4.27 for untreated silages. Above 260 g DM kg-1 both formic acid and sulphuric acid/formalin provided a small but consistent decrease in ammonia-N and pH compared with untreated silages. Chemical additive use conferred no other benefit when compared with untreated silage. Calcium formate/sodium nitrite mixtures and acid mixture use provided no benefit in fermentation compared with untreated herbage.

Notes: This work examined whether or not Holcus lanatus, cv. Massey Basyn, is an improvement on plants from German Commercial seed of this species and whether either could outyield Lolium perenne cv. Aberystwyth S23. The three grasses were sown in monoculture in a field near Oxford and received a total of either 250 or 500 kg N ha-1 over two years. They were also sown with Tri-folium repens cv. Blanca. The plots were cut 11 times over the 2-year period at a height of 50 mm from ground level.At the high rate of nitrogen Lolium perenne always gave the highest yields of DM and DOM. In the second year, both types of H. lanatus gave higher yields than L. perenne at the low level of N. The L. perenne and T. repens mixture yielded more than that with H. lanatus and T. repens. H. lanatus depressed the yield of T. repens more than did L. perenne. H. lanatus h lanatus; Massey Basyn was affected less by rust infection than was German Commercial H. lanatus. At the final harvest, plots with r. repens contained more unsown grass than did N-fertilized plots sown to grasses only.

Notes: Two experiments were carried out to examine the effects of grazing severity on the performance of January/February calved British Friesian dairy cows. In Experiment 1, three groups of cows were rotationally grazed across twenty-four one-day paddocks with high (H), medium (M) or low (L) herbage allowances. Cows on treatment M were offered a daily herbage allowance designed to achieve a residual sward height of 50 mm, assessed by a rising-plate sward stick. The daily herbage allowance (g organic matter (kg live-weight)-1 on treatments L and H were 0.30 below and above that for M, respectively, to give residual sward heights of 42 and 59 mm. In Experiment 2, three groups of cows were grazed across twenty-four one-day paddocks to obtain residual sward heights of 50 mm (severe), 60 mm (moderate) and 80 mm (lax).Average milk yields on the L, M and H treatments in Experiment 1 were 11.8, 14.6 and 14.5 kg d,-1 and in Experiment 2 they were 13.7, 16.0 and 17.0 kg d-1 on the severe, moderate and lax treatments, respectively. The results indicate that the critical herbage height below which milk production per cow declines may vary with the production potential of the animal. There were no significant treatment effects on milk composition.Milk output ha-1 and utilized metabolizable energy ha-1 were greatest with the low herbage allowance in Experiment I and the moderate treatment in Experiment 2. Net herbage accumulation on the severe treatment in Experiment 2 was 30% lower than that on the lax treatment, as a result of treading damage in early season.It is concluded that, in a rotational grazing system, a reasonable compromise between sward utilization and animal performance can be achieved by grazing January/February calved cows to a residual sward height of 60 mm as assessed by a rising-plate sward stick. This is equivalent to a sward surface height of about 80 mm.

Notes: The study compared two systems of silage harvesting, direct-cutting flail harvesting (flail-direct) or pre-cutting, followed by wilting and collection by a meter-chop harvester (precision-wilted). Each silage was self or easy fed to dairy cows. In addition, the response to protected soya bean meal included in the supplementary concentrate was also examined.Approximately 400 t of each of the two silages were produced from the same swards under good weather conditions with formic acid applied as an additive. The resulting silages were well preserved and had mean particle lengths of 43 and 29-mm, and D-values of 0-74 and 0-71 for the flail-direct and precision-wilted silages, respectively.During a 159-d feeding period commencing on 5 November, the silages were offered to 88 British Friesian cows in a 23 factorial design, continuous feeding experiment. The cows calved during the experiment and had a mean calving date of 18 January. The feeding treatments involved both silage types, two systems of silage feeding (self and easy) and two sources of protein in the supplementary concentrate given after calving (soya bean or 100 g kg-1 protected soya bean). No concentrates were offered pre-calving and all animals were given 7.6 kg d-1 concentrates post-calving.There were no significant interactions between the system of silage harvesting and feeding.Animals on the precision-wilted silage consumed 14% more silage dry matter (10.9 vs. 9.6 kg DM d-1) over the total period and by the end of the experiment were producing 7% less milk per day (25.4 vs. 27.2 kg). However, the responses in the output of total milk constituents (fat and protein) were lower than those obtained in milk yield. Animals offered silage by self feeding had similar dry matter intakes, but produced marginally less milk than those easy-fed.Ration digestibility and nitrogen utilization data, obtained from a concurrent change-over design experiment, suggested that the energy from the precision-wilted silage was less efficiently utilized for milk production.There was no significant response in either milk yield or composition to the inclusion of protected soya bean in the supplement.

Notes: Four management systems involving different dates for first harvest (simulated grazing, early silage, late silage and hay) and two fertilizer N rates in spring (0 and 80 kg ha-1) were imposed on a perennial ryegrass cv. Talbot/white clover cv. Blanca sward during 1981-82. In each year, annual total herbage DM was increased by spring application of N but white clover production and content in the total herbage were reduced; however, white clover, which was depressed in the harvests immediately after N application, recovered during the season to amounts and contents in the total herbage similar to those given no spring N.Annual total herbage DM production increased as the date of primary harvest was delayed (935 to 1197 t ha-1 over two years) but mean organic matter digestibility values for the same period decreased (0-769 to 0700). First-harvest production made up substantial proportions of the annual production in the conservation systems. White clover, as shown by its production and the amount of stolon present, was tolerant of conservation systems, especially with no applied N.It is concluded that grass/white clover swards are suitable for management systems which involve cutting for conservation. The use of strategic spring N seems a viable option, but more knowledge of rates would be valuable since this experiment only compared 80 kg ha-1 with no applied N.

Notes: A series of comparisons was made of the bite rates of fistulated and non-fistulated cattle and sheep, grazing four grassy hill plant communities over four years. Both bite rates and grazing times were recorded on two occasions. Comparative observations were also made on faecal cuticle concentrations on one grassy and one dwarf shrub community and on faecal ash, nitrogen (N) and acid detergent fibre (ADF) concentrations throughout one year.Faecal N concentrations were slightly but consistently higher in fistulates than in non-fistulates, but faecal ADF and ash concentrations and the relative proportions of faecal cuticle fragments were similar and did not indicate differences in either diet composition or digestive efficiency. Bite rates did not differ significantly between fistulates and non-fistulates, except on the two occasions when fistulates carried Vibracorders to measure grazing time without preliminary training, and grazing times did not differ significantly. There were significant differences between cattle and sheep in most variables.On the basis of this evidence, there is no reason to expect that fistulated and non-fistulated animals of similar history and nutritional background will differ in grazing behaviour or diet composition.

Notes: The yield of hay on the Palace Leas meadow hay plots has increased significantly with time on the higher yielding plots but has remained constant on the lower yielding plots. Yield on the higher yielding plots shows a relatively low fluctuation from year to year, and yields of plots treated with farmyard manure show high intercorrelations with each other, but lower correlations with the other plots. Yield is influenced by weather, but even the most successful climatic parameter– maximum soil moisture deficit—only accounts for 30% of the year on year variation in yield. There are highly significant autocorrelations between yields within each of the farmyard manure, treated plots indicating cyclic effects with periods of up to 6 years, but these are not related to the cyclic patterns of manure application.

Notes: In a 16-week winter feeding experiment, 48 autumn calving cows and heifers were used to compare a control diet, with two diets including fodder beet at a low and a high level. The control diet was ad libitum silage and 6 kg d-1 of concentrates (13.4 MJ (kg DM)-1 of ME and 197 g (kg DM)-1 of CP). The cows offered fodder beet were fed the control diet (C) plus fodder beet at either 2 (L) or 4 (H) kg DM d-1. Soya bean meal was offered with the fodder beet at 0.5 or 1.0 kg d-1 for diets L and H, respectively.Total dry matter and metabolizable energy intakes were 15.2,16.4 and 17.3 kg DM d-1; 177, 195 and 211 MJ d-1 for treatments C, L and H, respectively. The mean milk yields were not significantly affected by the feeding of fodder beet. There was a significant improvement in the fat and protein content of the milk and yield of constituents. The milk composition and yield of solids were: fat content 42.3,44.2 and 45.9 (s.e.d. 1.25) g kg-1; protein content 33.0, 34.5, 35.3 (s.e.d. 0.76) g kg-1; fat yield 964,1027,1095(s.e.d. 63.2); protein yield 757, 801, 841 (s.e.d. 48.8) for treatments C, L and H, respectively. The treatments had no significant effect on live weight or condition score change.

Notes: Data from six experiments conducted at two Agricultural Development and Advisory Service Experimental Husbandry Farms during 1980–83 were used to compare low dry matter (DM, 160 g kg-1), low water soluble carbohydrate (WSC, 15 g kg-1), non-additive treated silage with silage treated with commercial inoculants or formic acid with or without added formalin (formic acid ± formalin). Formic acid ± formalin significantly decreased silage pH and ammonia-N and significantly increased silage residual WSC compared with inoculant or untreated silage. Formic acid ± formalin significantly increased oven DM and significantly reduced DM loss during ensiling compared with untreated silage. Formic acid ± formalin treatment significantly increased both silage DM and total DM intake compared with untreated silage. Daily liveweight gains of cattle offered formic acid ± formalin were significantly higher than those given inoculant or untreated silage.It is suggested from the results that formic acid ± formalin additives can be used successfully to prevent a clostridial fermentation developing when crops contain 15 g WSC kg-1.

Notes: Following the Chernobyl accident in April 1986 137Cs was detected in samples of grass collected at AGRI, North Wyke, Devon, UK. Samples of grass from permanent and reseeded swards under uniform management were taken on three occasions. The 137Cs content of the samples was assessed as both Bq kg-1 of sample and Bq m-2, Samples taken from the same site in 1985 were used as a control group; these contained no measurable 137Cs. The samples taken on 8 May 1986 had a 137Cs content of approximately 30 Bq kg-1; by 31 July 1986 the content had dropped to 1% of this value. The permanent pasture initially showed a higher level of 137Cs than the reseeded sward. Analysis of soil cores from the sampling area showed a much higher level of 137Cs than that found in the herbage. This was attributed to the atmospheric testing of nuclear devices in the early 1960s: the short-lived 137Cs isotope was found in the 1986 herbage samples but not in the soil cores.

Notes: The effects of delayed emergence of white clover (cv. Grasslands Huia) seedlings, following slot-seeding during spring and early summer 1983, were simulated by sowing seeds at intervals into slots cut in turves of permanent grassland in soil-filled tanks or in the field. The resulting spread and growth of the species were assessed during the following 15–18 months. The effects of propyzamide, a grass-suppressing herbicide (at 0·2 kg ha-1), were also investigated in the field.A delay of 10 or 18 days in the sowing of seeds in turves in the tanks reduced clover dry weight yield from 23 to 11 during 1983 and from 118 to 96 g (0·12 m)-2 during 1984. Spread of stolons from the slots was also greatly delayed and effects persisted for at least a year. Increased clover growth on the earliest sown treatment more than compensated for a slightly smaller yield of grass.In the field, yields of clover from late summer 1983 until spring 1984 closely reflected the order of emergence. Afterwards, differences were less clear-cut but the cumulative yield of clover until August 1984 of the earliest-sown treatment was twice that of a treatment sown 20 d later. Effects of delayed sowing in summer 1983 were more pronounced on stolons than on foliage growth when measured in September 1984, with significant reductions in many stolon attributes even with 8 d delay in sowing. Application of propyzamide in autumn 1983 increased clover yield during 1984 from 1·7 to 3·0 and total herbage yield from 7·1 to 8·6 t ha-1.The results demonstrated some of the benefits of rapid seedling emergence and of the use of a grass-suppressing herbicide, but did not indicate any interaction between the two factors.

Notes: Experiments were carried out over four years to develop a system of buffer grazing. Groups of 16 cattle were set stocked with or without buffer areas formed by withholding a proportion of the grazing area by electric fence. It was found that buffers should be grazed if sward height, measured by rising plate meter, was reduced below 5 cm, or otherwise cut for silage. Increasing the area of the buffer reduced cattle gains but increased silage yield and sward quality, and the best compromise over 4 years was a buffer area of 25-30% of the initial grazing area. Buffer treatments gave higher UME and financial output than controls, due to the value of silage from the buffers and to the higher nitrogen inputs which were successfully managed under buffer grazing. The higher outputs over 4 years were also associated with lower viability and therefore lower levels of risk, resulting from a number of compensating processes at sward and animal level. There was no indication that grazed UME was higher on buffer treatments at a given level of nitrogen, suggesting that any increased grazing efficiency must be offset by other disadvantages when comparing intensive with lax defoliation regimes. The results suggest that there is considerable stability in grazing systems which may frustrate attempts to improve their biological efficiency, although there is some scope for manipulating the seasonal pattern of land use and animal performance.

Notes: The invertebrate groups which are of most significance in grassland are briefly reviewed. Factors influencing the abundance and composition of the fauna are considered together with the types of damage caused in grassland, the economic importance of such damage and beneficial effects on soil fertility.

Notes: The relationship between tillering of a vegetative grass stand and Leaf Area Index (LAI) has been studied during sward establishment of perennial ryegrass and Italian ryegrass with different seedling densities and nitrogen fertilizer rates and on established swards of tall fescue during winter and early spring after different dates of last cut in autumn.The different experiments on different species led to the conclusion that in every instance the tillering rate slows down as soon as the LAI reaches a value of 3 and terminates rapidly at higher LAI, which corresponds with the almost complete extinction of light at the level of the tiller buds. The results confirm the direct role of light on morphogenesis previously demonstrated by several authors. The existence of such a limit of LAI helps to explain some contradictory effects of temperature or nitrogen on tillering.

Notes: Two experiments, each lasting approximately 12 months, were carried out at North Wyke, Devon, in 1982-83 (A) and 1983-84 (B), to investigate various sward managements following oversowing of white clover (Trifolium repens, cv. Grasslands Huia) at 4 kg ha-1 with a Hunter Rotary Strip-Seeder in June or July into the stubble of a permanent grass sward following conservation. Experimental managements comprised cutting, grazing with wether sheep or grass suppression by herbicide, as appropriate, in late summer/autumn (Phase I), winter (Phase II) and spring/early summer (Phase III).During Phase I, there was no differential effect on clover stolon development of lenient grazing at approximately 4-weekly intervals or topping at the same frequency to a similar height. Early in Phase II of Experiment A, grazed paddocks became so badly poached that no differences occurred between grazing either to early January or throughout the winter. Under drier conditions in Phase II of Experiment B, continuous grazing at either five (L) or ten (H) sheep ha-1 had no immediate effect on clover stolon development, but in a silage cut in June, paddocks formerly stocked at the lower rate yielded 40% more DM than those at the higher rate.Experiment A compared the use of a grass-suppressing herbicide, propyzamide, applied at 0.6 kg a.i. ha-1 in either October or February; in Experiment B it was applied in October. Prophyzamide applied at either time in Experiment A increased the clover content of herbage regrowing after the end of the experimental period from 16% to 36% (s.e.d. ± 3.9). In Experiment B, October application raised the clover contents of herbage cut in June 1984 from 10% (H) and 17% (L) to 32% (s.e.d.±5.9), and stolon lengths per m2 at the end of the summer period from 33 (H) and 56 (L) to 86m (s.e.d. ± 11.7). However, the effect of spraying propyzamide on subsequent herbage yields was erratic, and appeared to depend on the incidence of frost after application.In Phase III of Experiment A, continuous grazing was compared with a silage cut in June. At the end of the experiment there were 31 m m-2 of clover stolon in silaged areas compared with only 2.5 m m-2 following grazing (s.e.d.±6.6). Clover content and herbage yields were also significantly higher following conservation. In Experiment B in the same period, rotational grazing with a 14- or 35-day recovery interval was compared with a silage cut in June, with or without 100 kg N ha-1 applied in March. Application of N to the conservation treatment reduced clover stolon length per unit area, and in the regrowth in the post-experimental period the conservation treatment without N had the largest clover content (31% compared with 16-23% for other treatments, s.e.d. ± 3.6)

Notes: A mathematical model of the production, harvesting and utilization of maize and grass silage on a dairy farm with an autumn-calving herd is described. Using the model the comparative costs and benefits of growing and feeding maize in place of grass silage are examined for three sites in southern England. It is concluded that a winter milk production system based on maize rather than grass should improve profits by at least £30, and possibly by as much as £80 cow-1. This financial improvement is attributable to higher feed intakes and lower harvesting and fertilizer costs with maize silage. Simulating the results over a 10-year period also revealed that the switch from grass to maize should lower the risks in terms of the annual variability of silage yields and herd profits. Furthermore, it would appear unnecessary to completely turn over from grass to maize production to realize a significant financial benefit. Setting aside just 25% of the conservation area to maize and feeding a mixture of maize and grass silage is projected to increase profits from winter milk production by £30 to £45 cow-1.

Notes: A large-scale sealed system for freeze-drying herbage is described. It utilizes the principle of sorption drying and is dependent upon the vapour pressure differential (VPD) between the herbage and the silica gel drying agent. Ice sublimes to vapour from the sample in a system operating at approximately – 10°C and the vapour is adsorbed by silica gel in an air stream recycled by a blower; equal masses (up to 50 kg each) of wet herbage and silica gel are used. The system is simple to construct and is relatively inexpensive.Approximately eight days drying time are needed to reduce moisture content from 90 to 10%. Twenty-four different species or cultivars of both temperate and tropical grasses and legumes sampled at several stages of maturity have been dried in the system. When snap-frozen herbage is freeze-dried by this process the physical and chemical changes that otherwise occur when herbage is harvested and prepared for evaluation can be reduced and sufficient material can be obtained to permit animal feeding studies as well as chemical analyses.

Notes: Temperature and daylength treatments have been used to investigate the apparent link between the potential for rapid leaf extension in spring and floral initiation and development in Lolium perenne (cv. Vigor). After growth at 5°C for 10 weeks (vernalization treatment) the leaves which developed at 15°C expanded significantly faster than non-vernalized controls under both long and short days. Under long days floral development was initiated in vernalized plants but under short days it was not. Specific leaf area was higher in vernalized than non-vernalized plants under long days.The photosynthetic capacity of leaves which developed on plants which had been previously vernalized and then grown at 15°C under long days was higher than non-vernalized controls when expressed on a leaf area and dry weight basis, but not on the basis of chlorophyll content. Vernalization followed by short days resulted in a smaller and non-significant increase in the photosynthetic capacity of leaves.Application of gibberellic acid (GA) as a spray to non-vernalized plants did not affect floral development but did increase the rate of leaf extension. The application of GA did not affect specific leaf area or photosynthetic capacity expressed on an area basis.

Notes: Spectral reflectance measurements were found useful in estimating the dry green biomass (DGB) in hayfields in eastern Québec, Canada. The calibrated measurements of reflectance obtained in the 650 and 800 nm bands (respectively defined as the RED and NIR indices), the NIR/RED ratio, and the ratio (NIR-RED)/(NIR + RED) were used to generate various regression models which explained between 74 and 90% of the variance in DGB. The proportion of legumes, grasses and herbs in the canopy had no apparent influence on the reflectance measurements or on the value of the models.

Notes: Ewe and lamb performance, herbage production and feed quality components on four late-flowering perennial ryegrass (Lolium perenne L.) varieties were assessed under a fixed stocking management at an upland site (305 m OD) in mid-Wales. Averaged over four years (1981–84) there was no significant difference (P〉0·05) between Aberystwyth S23, Aberystwyth Ajax, Perma and Meltra (tetraploid) in ewe and iamb liveweight gains. There were, however, considerable differences between varieties during individual years and their relative ranking also changed substantially over the four years. Lamb production on Perma was 22% more than on S23 in the first year but by the fourth year it was 21 % less than on the latter variety.Differences between varieties were observed in herbage production. Net herbage accumulation was 15% more on Meltra than on Ajax whilst the calculated quantity of OM consumed was 19% higher from Meltra than from both Ajax and S23. Net animal liveweight gains were positively correlated with herbage production (r = 0·95, P 〈 0·05) and DOM consumed (r=0·96. P〈0·05).

Notes: High rainfall and the corresponding low herbage DM content has been shown to adversely affect cattle intakes and production. This could arise from physical restrictions on intake or digestion rate, or other behavioural limitations such as reduced palatability. A knowledge of the reason for the intake reduction would assist in determining the optimum supplement to feed. Eight steers were offered four diets in a changeover design. The diets were: A, cut herbage; B, cut herbage with added surface water; C, as B but with a low dry matter (DM) forage supplement (silage); and D, as B but with a high DM forage supplement (hay). The addition of surface water to herbage reduced DM intake and feeding time but had no effect on biting rate or rate of intake. Neither hay nor silage was eaten in sufficient quantities to restore DM intake, even though the silage was of similar nutrient composition to the herbage.

Notes: Three diploid red clover cultivars—Sabtoron, Violetta and Essex—and three tetraploid, Hungaropoly, Teroba and Red Head, were sown separately in pure culture and with each of three companion grasses: timothy (Aberystwyth S48), tall fescue (Aberystwyth S170) and perennial ryegrass (Aberystwyth S24).The effects of fertilizer N on yield and on clover/grass ratio over a 2-year period (seventh and eighth harvest years) subsequent to 6 harvest years during which no N fertilizer was applied were investigated. The data for productivity and persistence have already been published (McBratney, 1981; 1984).Application of fertilizer N increased DM yields in the eighth year. In this year, the highest yield, 11·9t ha-1, averaged over the six clover cultivars, was given in association with tall fescue. Tall fescue contributed 90% of this yield. Clover content continued to decrease in all swards but the decrease was greatest in the swards receiving fertilizer N. The yield of clover DM averaged over the six cultivars under N treatment declined from 5·6t ha-1 in the seventh year to only 0·4t ha-1 in the eighth year.The results from this trial demonstrate the potential of red clover sown either pure or in mixture with a suitable perennial grass, to maintain high output of quality herbage over a 6-year period without the aid of fertilizer N. They further demonstrate that following decline in red clover content, both herbage yield and quality may be restored by the application of N fertilizer, particularly where the clover was seeded with a highly productive companion grass.

Notes: Seeds of six cultivars of white clover were sown in 1983 in slots in tares of permanent pasture in soil-filled tanks in spring and in small plots in the field during midsummer. The clover cultivars investigated were the large-leaved Olwin and Milk nova, the medium-leaved Grasslands Huia and Aberystwyth S100, and the small-leaved Kent Wild White and Aberystwyth S184. Seeds from an indigenous clover population were also sown in the tanks. All herbage was defoliated at three- to six-week intervals to simulate rotational grazing and assessments were made until autumn 1984.Leaf and stolon production and spread of stolons from the slots were more rapid in Milkanova, S184, Huia and Kent than in Olwen and S100 In the tanks, harvested yields of clover leaf and petiole were largest for Milkanova and Olwen and least for the indigenous population; both Olwen and S100 had a smaller percentage of their total weight outside the slot area than had the other varieties. In the field, Milkanova greatly out yielded all other varieties and S100 yielded the least, contributing 48 and 27%, resf actively, to total herbage yield. The yield of grass differed little between varieties in tanks but in the field it tended to be higher with the smaller than with the larger-leaved varieties. Total herbage yield was largest for Olwen and Milkanova in tanks and for Milkanova in the field. The greatest weight of stolons in tanks was produced by Olwen and in the field by Olwen and Kent, but the greatest length of stolons and number of nodes in both environments occurred in the smalt-leaved varieties, especially Kent. Least length of stolons and fewest nodes in the tanks were produced by Olwen and in the field by Milkanova.It was concluded that all the varieties investigated could be successfully slot-seeded into permanent pastures but that the choice of variety will depend on subsequent use and management of the resulting swards.

Notes: Ninety-six plots (3 × 2 m) of well-established perennial rye grass/white clover pasture were mown to heights of 2·7 (Low) or 3·96 (High) cm (rising plate meter) at 14-, 28-, 84- or 112-d intervals in autumn-winter. A 7-, 14- and 28-d mowing interval was superimposed in spring on each autumn–winter mowing interval treatment with the low and high mowing heights altered to 2·92 and 4·80 cm, respectively.With the low cutting height, accumulated herbage DM was more than doubled (1806 ± 79 kg DM ha-1) compared to a ‘high’ (754 ± 49 kg DM ha-1) cutting height in autumn–winter and this was due to increased harvesting efficiency rather than growth as estimated by leaf extension. Although defoliation interval had no effect on DM yield, the grass component increased and clover decreased. The composition effect carried over into spring. On average, 3·5 tillers were produced over winter for each ryegrass tiller present in autumn and tiller densities were higher in spring. Tillers produced over autumn–winter contributed more than 60% of ryegrass growth by early spring.In early spring (16–30 September), the low cutting height increased herbage DM yield, in mid-spring (1–14 October) it reduced DM yields particularly in combination with short defoliation intervals, while in late spring (14 October to 11 November) cutting height had no effect on DM yields.Over the entire spring period there was a very marked effect of defoliation interval on DM yields.

Notes: Although many aspects of grass silage have received intensive study, the changes that take place within the grass blades during ensilage have received little attention.In two factorial experiments Italian ryegrass (cv. Lemtal) and cocksfoot (indigenous) were ensiled in laboratory silos (capacity 0·2 kg) with the grass under pressure (700 Pa) and subjected to two treatments (with or without 3·31 t-1 85% formic acid) and two silos from each treatment opened on eight sampling dates(1,2,3,4,7,10,14 and 21 d).For each sampling date transverse sections of grass laminae were examined and changes in the cross sections of the protoplasts and of cells, as defined by the cell walls, were recorded. These data were used to calculate the ratios of protoplast to cell volumes at each sampling date.Each silage was analysed for dry matter, pH, lactic acid, VFA, ammonia and glucose. The distance settled by the silage (a measure of decrease in silage volume) and the silage conductivity were also recorded.Both of the untreated grasses yielded silages with typical lactic acid levels and pH values. In all of the silages there was a marked shrinkage of the plast within the space defined by the cell wall. The ratio of protoplast to cell volume eventually stabilized at 0·4. The formic acid-treated grasses reached this level by day 1 but a longer period was required by untreated grasses.It is suggested that the decrease in silage volume is related to the lactic acid content of the liquid phase due to their close relationship in silages produced from untreated grasses (r= 0·97***).

Notes: Thirty-six British Friesian heifers were divided into two groups during weeks 3-26 of lactation and received ad libitum either good (G) or average (A) quality grass silage. The in vitro digestible organic matter in the DM was 680 and 600 g kg-1 for silages G and A, respectively. In addition, the heifers in each group were offered concentrate at either a low (4.3 kg DM d-1), medium (64 kg DM d-1) or high (8.4 kg DM d-1) level. The concentrate contained 180 g (kg DM)-1 of crude protein and had a calculated metabolizable energy concentration of 12.9 MJ (kg DM)-1.Increasing concentrate level significantly increased milk yield (P 〈 0.01), milk protein concentration (P 〈 0.05), and yield of both milk protein depressed milk fat concentration (P 〈 0.001) and silage intake (P 〈 0.001).Although the overall effect of silage quality on milk yield was not significant, the milk yields for silage G at each concentrate level were higher, significantly so for low level, than the corresponding values for silage A. An improvement in silage quality did not affect milk fat concentration but significantly increased the concentration of milk protein (P 〈 005) and yields of both milk fat (P 〈 005) and protein (P 〈 0001). The response of silage DM intake to improved silage quality was 0 06 kg DM per 10 g rise in vitro DOMD value. Each additional kg concentrate DM depressed intake of silages G and A by 0-63 and 0-27 kg DM, respectively. Substitution rate was also significantly related to stage of lactation.With both silages, the digestibility coefficients determined in vivo for acid detergent fibre (ADF) decreased significantly (P 〈 0.001) when concentrate level was increased from low to high. Differences for DM, OM and total N digestibility coefficients between treatments were not established as significant at the 5% level.Estimates of mean efficiency of utilization of ME for lactation, made on a weekly basis, were 049 and 052 for the heifers given silages G and A. respectively, and 048, 052 and 052 for those given the low, medium and high levels of concentrate. Energy balances were calculated on a mean weekly basis.

Notes: Book reviewed in this articles: Maize Silage Edited by R. Phipps and M. Wilkinson The Elements of Graphing Data W. S. Cleveland, AT & T Bell Laboratories Fifteenth California Alfalfa Symposium